Refrigeration device comprising multiple storage chambers

ABSTRACT

A refrigeration device has at least one first and second storage chambers and a refrigerant circuit in which a first throttle point, a first heat exchanger for controlling the temperature of the first storage chamber, a second throttle point, and a second heat exchanger for cooling the second storage chamber are connected in series. A high pressure line section upstream of the first throttle point and a low pressure line section downstream of the second heat exchanger form a first inner heat exchanger. A bypass line extends parallel to the high pressure line section to the first heat exchanger, and a control valve is provided in order to control the distribution of the refrigerant to the high pressure line section and the bypass line.

The present invention relates to a refrigeration device, in particular a domestic refrigeration device, comprising a plurality of storage chambers which are able to be operated at different temperatures.

A refrigeration device comprising a plurality of storage chambers is disclosed in DE 10 2013 226 341 A1 in which a first throttle point, a first heat exchanger for controlling the temperature of the first storage chamber, a second throttle point and a second heat exchanger for cooling the second storage chamber are connected in series in a refrigerant circuit. The pressure loss at the second throttle point causes a pressure difference between the two heat exchangers, so that the evaporation temperature of the refrigerant in the second heat exchanger is lower than in the first heat exchanger, and thus a lower operating temperature is able to be adjusted in the second storage chamber than in the first storage chamber. The first heat exchanger may operate as an evaporator or as a condenser, depending on the adjustment of the first throttle point. If it is operated as a condenser, the operating temperature of the first storage chamber may attain values at room temperature or even slightly above room temperature.

It is known per se in order to improve the efficiency in a refrigeration device to provide an inner heat exchanger in which a high pressure line section, in which refrigerant heated by compression circulates, and a low pressure line section, in which refrigerant flows from an evaporator to a compressor, are in thermal contact. Such an inner heat exchanger, however, is useless if in a refrigeration device with a plurality of storage chambers, as described above, a first storage chamber is intended to be operated at a high temperature and to this end an evaporator of the storage chamber located in the refrigerant circuit downstream of the high pressure line section of the inner heat exchanger is operated as a condenser. Thus it is only possible to cool the second storage chamber with reduced energy efficiency.

It is the object of the present invention to provide a refrigeration device comprising a plurality of storage chambers which also permits an energy-efficient operation even when a high operating temperature is selected for a first storage chamber and a low operating temperature is selected for a second storage chamber.

The object is achieved in a refrigeration device comprising at least one first and one second storage chamber and a refrigerant circuit in which a first throttle point, a first heat exchanger for regulating the temperature of the first storage chamber, a second throttle point and a second heat exchanger for cooling the second storage chamber are connected in series, a high pressure line section upstream of the first throttle point and a low pressure line section downstream of the second heat exchanger form a first inner heat exchanger, a bypass line extends parallel to the high pressure line section to the first heat exchanger, and a control valve is provided in order to control the distribution of the refrigerant to the high pressure line section and the bypass line. If the first storage chamber is intended to be operated at a high temperature, the refrigerant may be diverted directly to the first heat exchanger via the bypass line; in order to achieve an energy-efficient operation of the first storage chamber at a low temperature, the refrigerant is conducted via the inner heat exchanger.

Expediently, the bypass line is also arranged parallel to the first throttle point. Thus, when the refrigerant circulates on the bypass line not only is it possible to prevent cooling by the inner heat exchanger but also adiabatic cooling at the throttle point.

The control valve may be a directional valve.

The directional valve may form an upstream or downstream end of the bypass line; preferably the directional valve forms the upstream end since here a small line cross section is sufficient and a more compact and more cost-effective valve may be used, while a valve on the downstream end has to have sufficient space in order to conduct refrigerant which is depressurized at the first throttle point without excessive pressure loss.

Alternatively, the control valve may be a shut-off valve arranged in the bypass line. In the closed state, such a shut-off valve forces the entire refrigerant flow via the inner heat exchanger; in the open state both paths via the inner heat exchanger and via the bypass line are passable but the effect of the inner heat exchanger is small, primarily if the first throttle point is located in series with the inner heat exchanger parallel to the bypass line and diverts the refrigerant into the bypass line.

As a result of a development, a third heat exchanger is arranged in a branch of the refrigerant circuit which extends to the second heat exchanger by bypassing the first and second throttle point and the first heat exchanger. Thus a third storage chamber may also be temperature-controlled.

In order to keep the third storage chamber at a different operating temperature from the first and the second storage chambers, preferably a third throttle point is connected upstream of the third heat exchanger in the branch and a fourth throttle point is connected downstream thereof.

A medium pressure line section which extends between the first heat exchanger and the second throttle point and a second low pressure line section may form a second inner heat exchanger. The second inner heat exchanger, in particular, contributes to an energy-efficient operation when the refrigerant is diverted past the first inner heat exchanger in order to keep the first storage chamber at a high operating temperature.

Alternatively, a third heat exchanger may be connected in the refrigerant circuit downstream of the first heat exchanger and upstream of the second heat exchanger.

In this case, a second inner heat exchanger may be formed by a medium pressure line section, which extends between the first heat exchanger and a third throttle point connected upstream of the third heat exchanger, and a second low pressure line section.

The control valve is coupled to a temperature sensor of the first storage chamber in order to control the distribution of refrigerant to the high pressure line section and the bypass line according to the temperature detected by the temperature sensor. Thus, if required, the temperature of the refrigerant which enters the heat exchanger of the first storage chamber may be varied and—if the bypass line also bypasses the first throttle point—if required it is also possible for the first heat exchanger to switch between condenser mode and evaporator mode. In this manner, in the first storage chamber operating temperatures may also be maintained which are close to ambient temperature and which are not able to be implemented reliably in the case of a fixedly predetermined position of the directional valve.

Further features and advantages of the invention are disclosed from the following description of exemplary embodiments with reference to the accompanying figures, in which:

FIG. 1 shows a schematic view of the refrigerant circuit according to a first embodiment of the refrigeration device according to the invention;

FIG. 2 shows a modification of a detail of FIG. 1; and

FIG. 3 shows a view of the refrigerant circuit according to a second embodiment.

The refrigerant circuit shown in FIG. 1 comprises a speed-controlled compressor 1 with a pressure connection 2 and a suction connection 3. A high pressure refrigerant line 4 from the pressure connection 2 initially runs in the circulation direction of the refrigerant via a condenser 5 and a branching 6 to a directional valve 7. A portion of the high pressure refrigerant line 4 leads from a first outlet of the directional valve 7 via an inner heat exchanger 8 and a first throttle point 9 to a heat exchanger 10 which is assigned to a first storage chamber 26 of the refrigeration device. A bypass line 11 connects a second outlet of the directional valve 7 directly to the heat exchanger 10, bypassing the inner heat exchanger 8 and the throttle point 9.

An outlet of the heat exchanger 10 is connected via a second inner heat exchanger 12 and a second throttle point 13 to a heat exchanger 14 which is assigned to a second storage chamber 27.

A low pressure refrigerant line 15 extends from an outlet of the heat exchanger 14 via the second inner heat exchanger 12 and the first inner heat exchanger 8 back to the suction connection 3.

The inner heat exchangers 8, 12 in each case comprise a section 16 and/or 17 of the low pressure line 15 and a section 18 of the high pressure refrigerant line 4 and/or a line section 19 at a medium pressure, which is fastened, for example soldered, in close thermally-conductive contact to the low pressure line section 16 and/or 17 or which is guided inside the relatively spacious low pressure line section 16 and/or 17. The high pressure and/or medium pressure sections 18 and/or 19 may in turn form part of the adjacent throttle point 9 and/or 13, for example by being configured as capillaries.

A third throttle point 21, a heat exchanger 22 assigned to a third storage chamber 28 and a fourth throttle point 23 are located on a line branch 20 which is separated at the branching 6 from the high pressure refrigerant line 4. In this case, a section 24 of the line branch 16 runs in the first inner heat exchanger 8 in thermal contact with the same low pressure line section 16 as the high pressure line section 18; alternatively it could form together with a different section of the low pressure line 15 a third inner heat exchanger. The line branch 16 terminates at a junction 25 downstream of the second throttle point 13 and upstream of the second heat exchanger 14.

The throttle points 9, 13, 21, 23 may all be configured as capillaries, with a fixed but unchangeable volume flow rate. However, in order to be able to control the intensity of the heat exchange between the storage chambers 26, 27, 28 and the refrigerant on the heat exchangers 10, 14, 22, as required, fans 29 are provided in the storage chambers 26, 27, 28, if required said fans blowing onto the heat exchanger 10, 14 and/or 22 assigned to the storage chamber.

Alternatively, expansion valves with a controllable volume flow rate may be used as throttle points 9, 13, 21, 23. The fans 29 are thus not absolutely necessary for controlling the temperatures of the storage chambers 26, 27, 28; nevertheless, the fans may be advantageously provided in order to control not only the temperature but also the air humidity in the storage chambers 26, 27, 28.

A further fan 30 may be provided on the condenser in order to intensify the heat exchange there, if required.

If the compressor 1 is in operation, compressed refrigerant reaches the branching 6 after having been initially cooled in the condenser 5. The refrigerant is liquid at least to a large extent and its temperature is higher than the ambient temperature by a few degrees, depending on the size of the condenser. A portion of the refrigerant flows via the throttle point 21, the heat exchanger 22 and the throttle point 23 to the heat exchanger 14 and from there back to the suction connection 3.

If the directional valve 7 is located in the position shown in FIG. 1, the remainder of the refrigerant flows via the inner heat exchanger 8 and the throttle point 9, the heat exchanger 10 and the throttle point 13 to the heat exchanger 14.

The pressure in the evaporator 14 is sufficiently low in order to permit an operation of the storage chamber 27 as a freezer compartment, and the pressure in the heat exchangers 10, 22 is between that of the condenser 5 and that of the heat exchanger 14 and permits an operation of the storage chambers 26, 28, for example, as a chiller compartment or as a normal refrigeration compartment. In order to produce higher temperatures in one of the storage chambers 26, 28, for example for operation as wine storage, the ambient temperature would reliably have to be sufficiently far above the desired compartment temperature.

If, however, the directional valve 7 is open toward the bypass line 11, the pressure difference between the condenser 5 and the heat exchanger 10 is negligible and the temperature which prevails in the heat exchanger 10 is the evaporation temperature of the refrigerant corresponding to the combined pressure of the condenser 5 and the heat exchanger 10. The heat exchanger 10 thus operates as a second condenser which discharges heat to the storage chamber 15. The storage chamber 26 in this manner reaches temperatures above ambient temperature and, therefore, may be used for rapid thawing or heating of food or cooking processes, for example for proving dough or preparing yoghurt.

In this operating state, the temperature of the refrigerant at the outlet of the heat exchanger 10 is generally still above ambient temperature. In this case, the second inner heat exchanger 12 ensures the cooling of the refrigerant before reaching the throttle point 13 and thus permits an efficient cooling of the storage chamber 27.

In a manner known per se, the storage chambers 26, 27, 28 may be provided in each case with a temperature sensor in order to control the rotational speed of the compressor 1 and the volume flow rates of the throttle points 9, 13, 21, 23 and/or the rotational speeds of the fans 29, using a comparison of the actual temperatures in the storage chambers 26, 27, 28 with set values adjusted by the user. As a result of a development of the invention a temperature sensor 31 of the storage chamber 26 additionally serves for controlling the directional valve 7: if this deviates significantly downward from the adjusted set value, while the directional valve 7 is in the position shown in FIG. 1 and none of the other storage chambers 27, 28 has a cooling requirement, then the directional valve 7 is switched in order to conduct hot refrigerant via the bypass line 11 into the heat exchanger 10. Conversely, the directional valve 7 is returned to the position of FIG. 1 when the inflow of the hot refrigerant permits the temperature of the storage chamber 26 to deviate significantly upward from the set value. In this manner, it is also possible to maintain set temperatures in the storage chamber 26 which are close to the ambient temperature and which, when the ambient temperature fluctuates, may sometimes be above the ambient temperature and may sometimes be below the ambient temperature.

FIG. 2 shows a detail of the refrigerant circuit of a refrigeration device according to a modified embodiment. The directional valve 7 of FIG. 1 in this case is replaced by a shut-off valve 32 in the bypass line 11. The path to the heat exchanger 10 parallel to the bypass line 11 via the high pressure line section 18 and the throttle point 9 is continuously open. The mode of operation of this refrigerant circuit does not differ substantially from that shown in FIG. 1. If the shut-off valve 32 is closed, similarly in this embodiment the refrigerant may only reach the heat exchanger 10 via the throttle point 9. If the shut-off valve 32 is open, the path via the throttle point 9 does not significantly contribute to the refrigerant flow.

FIG. 3 shows a simplified refrigerant circuit according to a second embodiment of the invention. Components of the refrigerant circuit which are denoted by the same reference characters as in FIG. 1 have in each case the same function as described with reference to FIG. 1. Also in this case the refrigeration device has three storage chambers 26, 27, 28 but the heat exchanger 22 of the storage chamber 28 and the throttle point 21 connected upstream of the heat exchanger 22 are inserted between the line section 19 of the second inner heat exchanger 12 and the throttle point 13, resulting in a series connection of the heat exchangers 10, 22, 14 of all three storage chambers 26, 27, 28. The construction of the refrigerant circuit is simplified relative to FIG. 1 since the branching 6, the throttle point 23 and the junction 25 are eliminated. The only restriction which has to be taken into account is that the set temperature of the storage chamber 26 in this case is not able to be lower than that of the storage chamber 28. In this case, the possibility of operating the storage chamber 26 at temperatures close to ambient temperature or above, is as in the refrigerant circuit of FIG. 1.

Naturally, here the directional valve 7 may also be replaced by a shut-off valve in the bypass line 11 and a temperature sensor of the storage chamber 27 may serve for controlling the position of the directional valve 7 or the shut-off valve.

REFERENCE CHARACTERS

1 Compressor

2 Pressure connection

3 Suction connection

4 High pressure refrigerant line

5 Condenser

6 Branching

7 Directional valve

8 Inner heat exchanger

9 Throttle point

10 Heat exchanger

11 Bypass line

12 Inner heat exchanger

13 Throttle point

14 Heat exchanger

15 Low pressure refrigerant line

16 Low pressure line section

17 Low pressure line section

18 High pressure line section

19 Medium pressure line section

20 Line branch

21 Throttle point

22 Heat exchanger

23 Throttle point

24 Line section

25 Junction

26 Storage chamber

27 Storage chamber

28 Storage chamber

29 Fan

30 Fan

31 Temperature sensor

32 Shut-off valve 

1-13. (canceled)
 14. A refrigeration device, comprising: a first storage chamber and a second storage chamber; a refrigerant circuit having a first throttle point, a first heat exchanger for regulating a temperature of said first storage chamber, a second throttle point and a second heat exchanger for cooling said second storage chamber connected in series; a high pressure line section upstream of said first throttle point and a low pressure line section downstream of said second heat exchanger together forming a first inner heat exchanger; a bypass line extending parallel to said high pressure line section to said first heat exchanger; and a control valve configured to control a distribution of a refrigerant in said refrigerant circuit between said high pressure line section and said bypass line.
 15. The refrigeration device according to claim 14, wherein said bypass line is arranged in parallel with said first throttle point.
 16. The refrigeration device according to claim 14, wherein said control valve is a directional valve.
 17. The refrigeration device according to claim 16, wherein said directional valve is disposed to form an upstream end of said bypass line.
 18. The refrigeration device according to claim 14, wherein said control valve is a shut-off valve arranged in said bypass line.
 19. The refrigeration device according to claim 14, further comprising a third heat exchanger arranged in a branch of said refrigerant circuit that extends to said second heat exchanger by bypassing said first throttle point, said second throttle point and said first heat exchanger.
 20. The refrigeration device according to claim 19, further comprising a third throttle point connected upstream of said third heat exchanger in the branch and a fourth throttle point connected downstream of said third heat exchanger.
 21. The refrigeration device according to claim 19, further comprising a second inner heat exchanger formed by a medium pressure line section, which extends between said first heat exchanger and said second throttle point, and a second low pressure line section.
 22. The refrigeration device according to claim 14, further comprising a third heat exchanger connected in said refrigerant circuit downstream of said first heat exchanger and upstream of said second heat exchanger.
 23. The refrigeration device according to claim 22, further comprising a second inner heat exchanger formed by a medium pressure line section, which extends between said first heat exchanger and a third throttle point connected upstream of said third heat exchanger, and a second low pressure line section.
 24. The refrigeration device according to claim 14, wherein at least one of said throttle points is configured to enable a capacity for fluid to pass through to be controllable.
 25. The refrigeration device according to claim 14, further comprising a fan assigned to at least one of said heat exchangers.
 26. The refrigeration device according to claim 14, wherein said control valve is coupled to a temperature sensor of said first storage chamber in order to control a distribution of refrigerant to said high pressure line section and said bypass line according to a temperature detected by said temperature sensor. 